Relative glucose metabolic rate higher in white matter in patients with schizophrenia
ABSTRACT There is increasing evidence demonstrating that circuits involving the frontal lobe, striatum, temporal lobe, and cerebellum are abnormal in individuals with schizophrenia, which suggests that metabolic activity in the white matter connecting these areas should be investigated.
The authors obtained [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) and matching T1-weighted magnetic resonance imaging (MRI) on 170 subjects. Participants were 103 normal volunteers and 67 unmedicated patients with schizophrenia (N=61) or schizoaffective disorder (N=6). The images were coregistered and warped to standard space for significance probability mapping.
Compared with normal volunteers, patients showed higher relative metabolic rates in the frontal white matter, corpus callosum, superior longitudinal fasciculus, and white matter core of the temporal lobe. Elevated activity in white matter was most pronounced in the center of large white matter tracts, especially the frontal parts of the brain and the internal capsule. The white matter elevation did not appear to be entirely related to changes in gray matter/white matter brain proportions, whole brain metabolic rate bias, or excess head motion in patients, but this cannot be ruled out without absolute glucose determinations. Patients also showed significantly lower relative glucose metabolism in the frontal and temporal lobes, caudate nucleus, cingulate gyrus, and mediodorsal nucleus of the thalamus relative to normal volunteers, which is consistent with earlier studies.
In comparisons of unmedicated schizophrenia patients with normal volunteers, relative metabolic increases are apparent in white matter in patients with schizophrenia as well as decreases in gray matter. Inefficiency in brain circuitry, defects in white matter leading to enhanced energy need, white matter damage, and alterations in axon packing density are among the possible explanations for these schizophrenia-related findings of relatively increased metabolism in white matter.
SourceAvailable from: Suleyman Akarsu01/2014; 6(3):1. DOI:10.5455/cap.20140121114707
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ABSTRACT: The etiology of schizophrenia is not precisely known; however, mitochondrial function and cerebral energy metabolism abnormalities were determined to be possible factors associated with the etiology of schizophrenia. Impaired mitochondrial function negatively affects neuronal plasticity, and can cause cognitive deficits and behavioral abnormalities observed during the clinical course of schizophrenia. The present study aimed to investigate the relationship between the clinical features of schizophrenia, and mitochondrial complex activation, based on measurement of mRNA levels in the NDUFV1, NDUFV2, NDUFS1, and UQCR10 genes involved in the peripheral mitochondrial complex. The study included 138 schizophrenia patients and 42 healthy controls. The schizophrenia group was divided into a chronic schizophrenia subgroup (n = 84) and a first-episode schizophrenia subgroup (n = 54). The symptoms profile and severity of disorder were evaluated using the Scale for the Assessment of Negative Symptoms (SANS), Scale for the Assessment of Positive Symptoms (SAPS), and Brief Psychiatric Rating Scale (BPRS). The level of mRNA expression of NDUFV1, NDUFV2, and NDUFS1 was significantly higher in the schizophrenia group than in the control group. The mRNA level of NDUFV2 was positively correlated with BPRS and SAPS scores in the first-episode schizophrenia subgroup. The findings showed that there was a positive correlation between gene mRNA levels and psychotic symptomatology, especially positive symptoms. Our results suggest that mRNA levels of the NDUFV1, NUDFV2, and NDUFS1 genes of complex I of the mitochondrial electron transport chain might become a possible peripheral marker for the diagnosis of schizophrenia.12/2014; 2(1):6. DOI:10.1186/s40303-014-0006-9
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ABSTRACT: White matter abnormalities in schizophrenia have been revealed by many imaging techniques and analysis methods. One of the findings by diffusion tensor imaging is a decrease in fractional anisotropy (FA), which is an indicator of white matter integrity. On the other hand, elevation of metabolic rate in white matter was observed from positron emission tomography (PET) studies. In this report, we aim to compare the two structural and functional effects on the same subjects. Our comparison is based on the hypothesis that signal fluctuation in white matter is associated with white matter functional activity. We examined the variance of the signal in resting state fMRI and found significant differences between individuals with schizophrenia and non-psychiatric controls specifically in white matter tissue. Controls showed higher temporal signal-to-noise ratios clustered in regions including temporal, frontal, and parietal lobes, cerebellum, corpus callosum, superior longitudinal fasciculus, and other major white matter tracts. These regions with higher temporal signal-to-noise ratio agree well with those showing higher metabolic activity reported by studies using PET. The results suggest that individuals with schizophrenia tend to have higher functional activity in white matter in certain brain regions relative to healthy controls. Despite some overlaps, the distinct regions for physiological noise are different from those for FA derived from diffusion tensor imaging, and therefore provide a unique angle to explore potential mechanisms to white matter abnormality.Brain Imaging and Behavior 01/2015; DOI:10.1007/s11682-014-9349-1 · 3.39 Impact Factor